Rapid hardening portland cement clinker composition

ABSTRACT

A rapid hardening portland cement comprising 40 - 60 percent by weight of 11CaO.7A12O3.CaF2 phase and 30 - 50 percent by weight of 3CaO.SiO2 solid solution phase as the main mineral composition thereof and a process for manufacturing it.

leer-89. AU 116 United States Patent 1 Mori et al.

[ 1 Oct. 23, 1973 RAPID I'IARDENING PORTLAND CEMENT CLINKER COMPOSITION[7 5] lnventors: Shigejiro Mori, Kawasaki; Hiroshi Uchikawa, Funabashi;Shunichiro Uchida, Tokyo, all of Japan [73] Assignee: Onoda CementCompany, Ltd.,

Onoda-shi, Yamaguchi, Japan 22 Filed: Dec. 15,1971

21 Appl. No.: 208,069

[30] Foreign Application Priority Data Dec. 28, 1970 Japan 45/120520[52] US. Cl 106/89, 106/100, 106/104 [51] Int. Cl C04b 7/02 PrimaryExaminer-James E. Poer Attorney-Norman F. Oblon et al.

[57] ABSTRACT A rapid hardening portland cement comprising 40 60 percentby weight of 1lCaO-7Al O -CaF phase and 30 50 percent by weight of3CaO-Si0 solid solution phase as the main mineral composition thereofand a process for manufacturing it.

4 Claims, 8 Drawing Figures Compressive Strength of Morior (kg/cmPATENIED BB! 23 I913 SHEET 2 f 5 1 l I L 10 2o so c s in Clinker FIG.3

Compressive Strength of Morfor (kg/cm IO 20 3O 40 C 5 in ClinkerPATENTEU BUT 2 3 I973 Bending Strength of Mortar (kg/cm CompressiveStrength of Mortar (kg/crn IOO SHEET 30? 5 FIG.4

2 O l l l 5 IO 20 3O c s iri Clinker FIG.6

c s in Clinker RAPID HARDENING PORTLAND CEMENT CLINKER COMPOSITION Thisinvention relates to rapid hardening portland cement clinker compositioncontaining calcium fluoaluminate represented by llCaO' 7Al,O,'CaF=(hereinafter abridged as C A-,-CaF,).

An object of this invention is to provide clinkerfor producing rapidhardening portland cement which, after mixing with water, has a rapidhardening rate, a short but controllable initial setting time and thehigh compressive and bending strength both at short and longer period byadding anhydrite and hemihydrate thereto.

Further and additional objects of this invention will appear from thefollowing description.

The hardening rate or the strength of cement is generally greatlyaffected by the compound composition: that is, CaO'Al,O;, (hereinafterabridged as CA) and l2CaO-7Al,O (hereinafter abridged as C A have activehydraulic property and they set fast; therefore, it has been attemptedto use the clinker containing CA and C,,A-, phase for obtaining the highinitial strength of cement and the clinker containing 3CaO'SiO, solidsolution phase (hereinafter abridged ae C 8) and 2CaO-SiO solid solutionphase (hereinafter abridged as C 8) are utilized to obtain the highearly and later strength of cement. In order to obtain the cement havinggood strength development for all stage from initial to early and later,many workers have tried to use the mixture of aluminous cement clinkercontaining CA and C,,A and portland cement clinker containing C 8 and C8. However, it is difficult to control setting time, in such a mixedcement, and in some cases it sets very rapidly, in other case it setshardly. Even in the case that high initial strength of the cement can bedeveloped satisfactorily, hexagonal calcium aluminate hydrate thereoftransfers gradually to cubic 3CaO-Al- O '6I-I O accompanying with thereduction of strength which bring collapse and thus mixing ofabovementioned both cement clinkers has been thought to be harmful forsetting and hardening.

The present inventors have found that even if mixed raw materials isunder the high lime concentration C A-rCaF is formed as a stable phase,instead of GA in the burned clinker when fluoride such as fluorite isadded to mixed raw material.

So they prepared various kinds of rapid hardening portland cement fromthe clinkers which contain C A-rCaF, phase, C 5, C 5 and2CaO-Fe,O,-6CaO-' 2Al,O -Fe,o,. solid solution phase (hereinafterabridged as C AF), and studied a method of the regulation of the settingtime and a development of the high intital and later strength. As theresult, there was found out that the cement produced from the clinkercontaining 40-60percent by weight of C A-rCaF and 30-50 percent byweight of C 8 showed the high initial and later strength, and only inthe case when the content of Fe,0, in clinker is less than 3.0 percent(less than about 8 percent C AF), bending strength of mortar specimen isremarkably increased.

According to this invention, gypsum adding to the clinker was preferableto be a mixture of hemihydrate and anhydrite, and the total amountthereof was the most preferable in the range of 1 1-21 percent by weightbased on $0; in the cement and the adding ratio The setting time couldbe controlled by varying above-mentioned mixing ratio.

The above-mentioned clinker containing calcium flue-aluminate phase isproduced by burning a mixture of an aluminous material, a calcareousmaterial, a silicious material and a fluorite. The mixture comprisesmainly 20-33 percent by weight of A1 0 7.2-1 5 .5 per cent by weight ofSiO,, 52-62 percent by weight of CaO, 1.3-2.6 percent by weight of F andless than 3 percent by weight of n.0,, which is burned at thetemperature of l240-l 360C.

The compressive strength of the mortar, prepared from rapid hardeningportland cement which is produced by adding a mixture of hemihydrate andanhydrite to the clinker obtained by this invention, was higher thanabout 50-200 kg/cm at 3 hours and higher than about 100-250 kg/cm at oneday, and the bending strength of the mortar was higher than 10-30 kg/cmat 3 hours and higher than about 30-60 kg/cm at one day. Theexperimental results will be explained in detail as follows;

FIG. 1 shows relation between C A 'CaF, content in clinker and thecompressive strength of mortar, when c 8 content in clinker was selectedto be 30 percent by weight.

FIG. 2 to FIG. 4 show relation between C S content in clinker and thecompressive strength of mortar, when C A -CaF content in clinker wasselected to be 40, 50 and 60 percent by weight respectively.

FIG. 5 shows relation between C A-rCaF, content in clinker and thebending strength of mortar, when C 8 content in clinker was selected tobe 30 percent by weight.

FIG. 6 shows relation between the bending strength of mortar and C Scontent in clinker, when C A -CaF content in clinker was selected to be40 percent by weight.

FIG. 7 and 8 show relation between Pep, content in clinker and thebending strength of mortar, and between Fe O content and the compressivestrength of mortar, when the clinker contained 50 percent by weight of CA 'CaF, and 35 percent by weight of C S.

As the mixed raw materials producing the clinker pure chemicals weremixed so as to obtain the mineral composition shown in Table 1, groundin a porcelain potmill, shaped under pressure of 200 kg/cm to form I theflake of l 4 6cm, and burned at the temperature of l3l0-l350C in largesiliconite electric furnace so as to prepare clinker containing lessthan 0.5 percent by weight of F-CaO. The obtained clinker was ground ina ball mill to have Blaine specific surface area of 3700 cm /g, and amixture of hemihydrate and anhydrite was added to the powdered clinkerso that the prepared cement set in about 15 minutes after mixing withwater. The mortar strength test of the cement was tried out according toJIS R 5201 Testing Method.

In Table 2 and 3, there were list up the mortar strength at aged 3, 6hours and l day when C 8 content in clinker was kept a constant value of30 percent by weight, but C A -CaF content in clinker was varied, andthe mortar strength at aged 1 day and longer when C A 'CaF, content inclinker was kept constant but C S content was varied.

wet W... was.

TABLE 1 Mineral composition of clinker (percent by weight) ChemicalComposition (percent by weight) u 7 No. ms 028 can c.AF s102 A1203 F020nC30 MgO 100 1 13.0 F T0101 TABLE 2 TABLE 3 40 M17161?! MineralComposition Mortar Strength (kg/cm) s f i e of Clinker by weight) I(percent by Mortor setting No. I

weight) Mortar strength (kg/cm time (min.) C u w z 1 y 3 y 7 y 23 y 4-110 40 123 159 104 130 45 (20.7 34.0) (30.4 30.9) No. C35 CBF: 3 h. 6 h.1 day Initial Final 15 (2; Q75 (34 2 (35 9; (35 3 30 10 12.4 29.8 39.7l6 2| 20 2 82 1 (0.4) (7.3) -7) 2 30 15 14.9 49.5 00.0 15 23 25 3 172178 I00 (8.5) 02.2) 4. 30 9 111 181 282 223 3 30 20 27.0 55.1 T22. 10 2150 1 i 32.2 30.7 (40.4) 45.0) 30 25 52.0 03% 10 2 6) 14 20 35 6 53 5 3030 3%.? 03:5 111 15 21 2.86 3.33 (7.8) (14.0) 22.8) (37.3) 50.3) 00.574.0 0 30 35 45.0 08.4 118 15 21 45 3 (8.3) 15.1) 27.4) 55 u (8 7 30 4057 8 110 141 10 24 264 325 354 (38.5) (60.0) 75.6) 82.3) (12.9) (20.0)(32.2) 8 30 45 103 198 204 14 20 50 235 256 247 (17.5) (42.5) (01.2) 2'5f, if} 33; :2? 9 30 50 150 212 278 15 20 Note: Figures show values ofthe compressive strength. Figures in the parenthesis show the bendingstrength.

According to the results described above, the initial compressivestrength of the cement produced by the clinker containing more then 40percent by weight of C A- CaF, obviously increased and was higher than200 kg/cm at aged 3 hours. The initial compressive strength developmentof the cement produced by the clinker containing more than 60 percent byweight of C A-,'CaF, increased remarkably, but the strength developmentat 3 days and longer tended to reduce, to show undesirable behaviour ascement for building. (See P10. 1 to FIG. 4)

As to C 8 content in clinker, when it was more than 30 percent byweight, the strength of the cement after 1 day developed highly, and thestrength development at 7 and 28 days was remarkably. (See FIG. 2 toFlG.

As to the bending strength, it was observed that the bending strength ofthe cement produced by the clinker containing more than 40 percent byweight of C A-f CaF,, more than 30 percent of C S and less than 3percent by weight of n.0,, developed highly. (See FIG. to FIG. 8)

By selecting the clinker composition as described in this invention, thehigh initial and later compressive strength and bending strength of thecement produced by the clinker, can be obtained.

The effect of this invention can be recognized only with the compositionof clinker, but even if the same cement composition as that of cementproduced from the clinker of the invention is prepared by mixing normalportland cement clinker and the clinker containing enriched C,,A,-CaF,phase, the above-mentioned effect can not be expected from the cementobtained. For example, in case of the clinker composition, in

which 45 percent by weight of C A-,-CaF, and 40 percent by weight of C Sare prepared by mixing the clinker containing about 80 percent by weightof C m-Cal and high eary strength portland cement clinker, thecompressive strength of the cement produced from the clinker is measuredas follows.

As seen in Table 4, the compressive strength is found to descendgradually with time.

Some examples are shown below, and the chemical composition of rawmaterials used in the examples are the same as that shown in Table 5.

EXAMPLE 1 Lime stone, white clay bauxite, copper slag and fluoritehaving the chemical compositions shown in Table 5 were groundseparately, and mixed to make the chemical composition shown in Table 6No. 1. The mixed raw materials were shaped with a pan pelletizer,

and the pellets were continuously fed to a small-scaled rotary kilnhaving 60cm in diameter and 8m in length and burned at the clinkertemperature of 1300-l340C in the burningzone to produce clinker. Theobtained clinker contained the mineral composition shown in Table 6 No.1 and formation of C -,A was hardly observed by X-ray diffractionanalysis.

The clinker was ground, to which hemihydrate and anhydrite having thechemical composition shown in Table 7 were added amounts shown in Table8, No. 1

to prepare rapid hardening portland cement. The cement mortar testthereof was carried out according to 11$ R 5201 1964 and the resultsshown in Table 8 No. 1 were obtained.

TABLE 5 Residue of the Raw 88p. sieve material lg.1oss SiO A1 0; FeZO,Total (percent) White clay 4.3 73.8 20.3 0.3 99.8 1.1 Limestone 42.2 0.70.8 .1 100.0 1.8 Quick lime 4.5 4.1 1.2 .7 100.0 1.6 Bauxite 0.4 10.085.9 1.2 100.5 1.2 Fluorite 6.1 23.1 4.1 1.6 104.4 Copper slag 35.7 4.642.9 100.6 2.0

TABLE 6 Clinker mineral Chem cal component (percent) (percent) No, 1g.loss lnsol SiO A1 0 Fe Oa CaO MgO Na O K 0 SO: F TiO Total F CaC C SCHA'ICaFg 0.4 0.2 13.1 22.5 2.1 58.8 0.6 0.08 0.07 0.3 1.3 0.6 100.0 0.339 41 .3 .2 9.4 28.4 1.8 56.2 .5 .10 .08 .4 1.9 .8 100.1 .3 34 54 .3 .210.9 25.3 2.5 57.9 .5 .07 .09 .3 1.8 .6 100.5 .4 49 46 TABLE 7 lg.1ossSit), A ()=.+Fe-)O (a0 MgO Total (percent) (percent) (percent) (percent)(percent) (percent) (percent) Natural anhydrite 2.6 7.1 3.3 34.9 2.149.5 99.4 Hemrhydrate" 6.1 1.8 0.9 37.5 0.2 53.6 100.1

Prepared from natural gypsum by dehydration.

2. A rapid hardening cement clinker claimed in claim 1, in which lower than 3 percent by weight of Fe2O3 are comprised in addition to said mineral compositions.
 3. A process for manufacturing a rapid hardening cement clinker which consists essentially of mixing mainly an aluminous material, a calcareous material, a silicious material and a fluoride so as to make 20 - 33 percent by weight of Al2O3, 7.2 -15.5 percent by weight of SiO2, 52 - 62 percent by weight of CaO and 1.3 - 2.6 percent by weight of F, and burning the mixture at the temperature of 1260* - 1360*C.
 4. A process claimed in claim 3, in which less than 3 percent by weight of Fe2O3 in addition to said mixture present therein. 